The overall objectives of the project are to identify and characterize carcinofetal antigens and proteins of the gastrointestinal tract. Work this coming year will be devoted to further studies of the antigenic determinants of Carcino-Embryonic Antigen by haptene inhibition, and characterization of an unusual molecular form of serum carcino-embryonic antigen. We intend to test a number of other synthetic glycopeptides, of known chemical structure, by haptene inhibition radioimmunoassay for CEA. We also intend to test several additional antisera to CEA for their ability to recognize the unique CEA antigenic determinants described above. We hope to further characterize this unique serum CEA-like material initially by sephadex gel filtration, perchloric acid solubility and isoelectric point. If enough sera containing the CEA-like antigen can be obtained, we hope to perform further purification and chemical analysis of this CEA-like antigen.